Great for reviews and selling gear - this is one of the few forums that allow you to post your own gear and sell/trade it, for that reason alone it is worthwhile joining the community. Once people know you, they are more willing to buy your used gear. Better than ebay or craigslist for buying equipment.
Good source for photograph critiques. Professional photographer forum with software and camera information second to none. Well run website with good management. Contests weekly and monthly as well as forums dedicated to specific interests. The site has a location for photographers to buy and sell equipment. One great site.
This is the website for pros - This has some of the best collection of photography knowledge on the net. Fred does a wonderful job staying current with new trends in photography. Somehow this site has collected some of the best photographers online.
Answer: Are you only interested in Nikons? If you have only used film SLRs you will probably want a DSLR that is full frame. The Nikon D300 is a great camera and if you shoot Nikon it is highly recommended and has auto and manual mode. I used to shoot Nikon but switched to Canon. Specifically the canon 5D MII... it has full frame 21MP and shoots HD video as well. It is roughly around the D300 price, but really can last you for years. The 21MP is very nice as it allows you to crop more and if you want to do wall size enlargements of your photos it is useful. The other camera that the entire industry is buzzing about is the new Olympus Pen. It has interchangable lenses but is NOT an SLR. Here is the deal... you don't really need it to be an SLR in the digital world and this allows a much smaller camera and lens... great for travel.